The systems and method discussed herein treat tissue in the human body. In a particular variation, systems and methods described below treat cosmetic conditions affecting the skin of various body parts, including face, neck, and other areas traditionally prone to wrinkling, lines, sagging and other distortions of the skin.
Exposure of the skin to environmental forces can, over time, cause the skin to sag, wrinkle, form lines, or develop other undesirable distortions. Even normal contraction of facial and neck muscles, e.g. by frowning or squinting, can also over time form furrows or bands in the face and neck region. These and other effects of the normal aging process can present an aesthetically unpleasing cosmetic appearance.
Accordingly, there is well known demand for cosmetic procedures to reduce the visible effects of such skin distortions. There remains a large demand for “tightening” skin to remove sags and wrinkles especially in the regions of the face and neck.
One method surgically resurfaces facial skin by ablating the outer layer of the skin (from 200 μm to 600 μm), using laser or chemicals. In time, a new skin surface develops. The laser and chemicals used to resurface the skin also irritate or heat the collagen tissue present in the dermis. When irritated or heated in prescribed ways, the collagen tissue partially dissociates and, in doing so, shrinks. The shrinkage of collagen also leads to a desirable “tightened” look. Still, laser or chemical resurfacing leads to prolonged redness of the skin, infection risk, increased or decreased pigmentation, and scarring.
Lax et al. U.S. Pat. No. 5,458,596 describes the use of radio frequency energy to shrink collagen tissue. This cosmetically beneficial effect can be achieved in facial and neck areas of the body in a minimally intrusive manner, without requiring the surgical removal of the outer layers of skin and the attendant problems just listed.
Utely et al. U.S. Pat. No. 6,277,116 also teaches a system for shrinking collagen for cosmetically beneficial purposes by using an electrode array configuration.
However, areas of improvement remain with the previously known systems. In one example, fabrication of an electrode array may cause undesired cross-current paths forming between adjacent electrodes resulting in an increase in the amount of energy applied to tissue.
Thermage, Inc. of Hayward Calif. also holds patents and sells devices for systems for capacitive coupling of electrodes to deliver a controlled amount of radiofrequency energy. This controlled delivery of RF energy creates an electric field through the epidermis that generates “resistive heating” in the skin to produce cosmetic effects while simultaneously attempting to cool the epidermis with a second energy source to prevent external burning of the epidermis.
In such systems that treat in a non-invasive manner, generation of energy to produce a result at the dermis results in unwanted energy passing to the epidermis. Accordingly, excessive energy production creates the risk of unwanted collateral damage to the skin.
In addition, many existing cosmetic procedures involving the application of RF energy to skin tissue causes temporary discomfort to the patient during application of the treatment. In response, the physician applies topical or oral anesthesia to assist in pain management. However, the administration of topical or oral anesthesia requires time for the anesthesia to take effect and in many cases the effect is not sufficient to alleviate patient discomfort. In many RF based procedures, the use of local or injected anesthetics such as lidocane or similar substances is not an option as the injected anesthetic changes the electrical impedance of the target tissue. This change in electrical impedance directly affects the manner in which the tissue heats as RF energy is applied. Conventional systems are unable to adapt to such changes and might cause an unpredictable heating profile. This unpredictability can result in an increased risk of injury, ineffective treatment, and/or cause a cosmetically undesirable effect.
In view of the above, there remains a need for an improved energy delivery system. Such systems may be designed to create an improved electrode array delivery system for cosmetic treatment of tissue. In particular, such an electrode array may provide deep uniform heating by applying energy to tissue below the epidermis to cause deep structures in the skin to immediately tighten. There also remains a need to provide systems that can deliver energy to a predetermined target area while minimizing delivery of energy to undesired region of tissue.
Over time, new and remodeled collagen may further produce a tightening of the skin, resulting in a desirable visual appearance at the skin's surface. Such systems can also provide features that increase the likelihood that the energy treatment will be applied to the desired target region. Moreover, devices and systems having disposable or replaceable energy transfer elements provide systems that offer flexibility in delivering customized treatment based on the intended target tissue.
The systems of the present invention are also adapted to apply energy selectively to tissue to spare select tissue structures, to control creation of a lesion from a series of discrete lesions to a continuous lesion, and to selectively create fractional lesions to optimize effectiveness of the treatment.
Moreover, the features and principles used to improve these energy delivery systems can be applied to other areas, whether cosmetic applications outside of reduction of skin distortions or other medical applications.